1. Field of the Invention
The present invention relates to an inorganic thin film layer which is composed of an inorganic composite containing at least two kinds of inorganic materials and shows excellent moisture and oxygen barriers, an organic electroluminescence device including the inorganic thin layer as a passivation layer, and a fabrication method thereof.
2. Description of the Background Art
An Organic Light-emitting Diodes (OLEDs) are a self light emitting type, not a light receiving type like a thin film transistor-liquid crystal display (TFT-LCD). The OLED is advantageous in a response time, power consumption and brightness. Therefore, the OLED has been considered as a flat panel display replacing a liquid crystal display (LCD). The OLED is classified into a transparent OLED (TOLED), a flexible OLED (FOLED), a stacked OLED (SOLED), and a microcavity OLED (MOLED) according to functions, and into a passive mode OLED (PM-OLED) and an active mode OLED (AM-OLED) according to driving types.
A general fabrication method of the OLED will now be explained. An anode electrode is deposited on a glass or plastic substrate, and electrode patterns are formed thereon. An organic layer comprised of a hole injection layer, a hole transfer layer, a light emitting layer and an electron transfer layer is formed on the patterned electrode. A metal electrode which is a cathode electrode is deposited on the organic layer.
In order to prevent degradation and non-emissive dark spot of the organic layer by moisture or oxygen, a passivation layer has been suggested to be formed on the surface of the OLED. Exemplary methods for forming the passivation layer include a method for encapsulating a device with a metal can, and a method for spin-coating organic polymer materials. However, the encapsulation method is very complicated and not applied to a large area and flexible display.
In addition, deposition of SiO2 and SixNy was developed to form the passivation layer. However, a process for depositing SiO2 and SixNy requires a high temperature, and thus due to crystallization of the organic layers of the OLED. In the case that an inorganic thin layer such as SiO2 and MgO is formed by using a general vacuum evaporator, it is difficult to completely implement physical properties of the material itself. Accordingly, even though the inorganic thin layer is formed as the passivation layer of the OLED, it is not efficiently operated due to a high oxygen transmission rate (OTR) and a high water vapor transmission rate (WVTR).